J/A+A/562/A2 100-month Swift catalogue of SFXTs (Romano+, 2014)
The 100-month Swift catalogue of supergiant fast X-ray transients.
I. BAT on-board and transient monitor Flares.
Romano P., Krimm H.A., Palmer D.M., Ducci L., Esposito P., Vercellone S.,
Evans P.A., Guidorzi C., Mangano V., Kennea J.A., Barthelmy S.D.,
Burrows D.N., Gehrels N.
<Astron. Astrophys. 562, A2 (2014)>
=2014A&A...562A...2R 2014A&A...562A...2R
ADC_Keywords: X-ray sources ; Binaries, X-ray ; Surveys ; Stars, supergiant
Keywords: X-rays: binaries - catalogs - binaries: close - stars: neutron
Abstract:
Supergiant Fast X-ray Transients (SFXTs) are High Mass X-ray Binaries
(HMXBs) that are defined by their hard X-ray flaring behaviour. During
such flares they reach peak luminosities of 1036-1037erg/s for a
few hours (in the hard X-ray): much shorter timescales than those
characterizing Be/X-ray binaries. We investigate the characteristics
of bright flares (detections in excess of 5σ) for a sample of
SFXTs and their relation to the orbital phase.
We have retrieved all Swift/BAT Transient Monitor light curves, and
collected all detections in excess of 5σ from both daily- and
orbital-averaged light curves in the time range 2005 February 12 to
2013 May 31 (MJD 53413-56443). We also considered all on-board
detections as recorded in the same time span and selected those within
4 arcmin of each source in our sample and in excess of 5σ.
We present a catalogue of over a thousand BAT flares from 11 SFXTs,
down to 15-150keV fluxes of ∼6x10-10erg/cm2/s (daily timescale)
and ∼1.5x10-9erg/cm2/s (orbital timescale, averaging ∼800s) and
spanning 100 months. The great majority of these flares are
unpublished. This population is characterized by short (a few hundred
seconds) and relatively bright (in excess of 100mCrab, 15-50keV)
events. In the hard X-ray, these flares last in general much less than
a day. Clustering of hard X-ray flares can be used to indirectly
measure the length of an outburst, even when the low-level emission is
not detected. We construct the distributions of flares, of their
significance (in terms of sigma) and their flux as a function of
orbital phase, to infer the properties of these binary systems. In
particular, we observe a trend of clustering of flares at some phases
as P_orb increases, as consistent with a progression from tight,
circular or mildly eccentric orbits at short periods, to wider and
more eccentric orbits at longer orbital periods. Finally, we estimate
the expected number of flares for a given source for our limiting flux
and provide the recipe for calculating them for the limiting flux of
future hard X-ray observatories.
Description:
The BAT observes 88% of the sky daily, on average, so it is ideally
suited to detect flaring in hard X-ray sources. Since 2005-02-12 the
BAT Transient Monitor (Krimm et al. 2013, 2013ApJS..209...14K 2013ApJS..209...14K) has
been providing near real-time light curves in the 15-50 keV energy
range of more than 900 sources with a mean variance for one-day
mosaics of 5.3mCrab. Several flares from SFXTs are regularly caught
every year by the BAT Transient Monitor.
The catalogue file contains a total of 1117 flares from 11 SFXTs
sources. They are divided into 46 BAT triggers (T, 43 in outbursts),
126 daily-averaged BATTM light curves (D), 267 orbital-averaged BAT
Transient Monitor light curves (o), 678 on- board detections (d). For
each we report time of occurrence, duration, flux, and significance.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sample.dat 87 12 Sample of confirmed SFXTs: positions and
optical counterparts
table4.dat 93 1117 The 100-month Swift Catalogue of SFXTs
table4.fit 2880 32 FITS version of table4
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See also:
J/ApJ/687/1230 : SFXTs observed by Swift. I. Outside outbursts (Sidoli+ 2008)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/A+A/510/A48 : Palermo Swift-BAT Hard X-ray Catalogue (Cusumano+, 2010)
J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
J/A+A/551/A142 : 7 year Swift-XRT point source cat. (1SWXRT) (D'Elia+, 2013)
J/ApJS/209/14 : The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)
http://www.ifc.inaf.it/sfxt/ : SFXT Home Page
Byte-by-byte Description of file: sample.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Source name
16 A1 --- n_Name [*] IGRJ11215-5952 never triggered the BAT
18- 19 I2 h RAh Right ascension (J2000)
21- 22 I2 min RAm Right ascension (J2000)
24- 29 F6.3 s RAs Right ascension (J2000)
31 A1 --- DE- Declination sign (J2000)
32- 33 I2 deg DEd Declination (J2000)
35- 36 I2 arcmin DEm Declination (J2000)
38- 42 F5.2 arcsec DEs Declination (J2000)
44- 47 F4.2 arcsec ePos Error on position
49- 71 A23 --- Ctp IR/optical counterpart
73- 87 A15 --- SpType MK Spectral type of counterpart
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [1/1117] Unique line identifier
6- 20 A15 --- Name Source name
22 A1 --- Flag [TDod] BAT data subsample flag (1)
24- 27 I4 yr Obs.Y [2005/2013] Year (YYYY)
29- 31 I3 d Obs.D [1/366] Day of Year (DDD)
33- 43 F11.5 d MJD [53418/56444] Modified Julian Date
45- 54 A10 "Y-M-D" UT.date UT date
56- 63 A8 "h:m:s" UT.time UT time
65- 72 F8.1 s Dur ?=999999 Flare duration
74- 78 F5.2 --- Signi Flare significance in sigmas
80- 86 F7.1 mCrab Fmean ?=99999 Mean flux (15-50keV)
88- 93 I6 --- Trigg ?=999999 BAT Trigger Number
(unavailable for not BAT triggers)
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Note (1): Flag discriminating the subsample as follows:
T = BAT trigger
D = from daily-averaged BATTM light curves
o = from orbital-averaged BATTM light curves
d = from on-board detections
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Acknowledgements:
Patrizia Romano, patrizia.romano(at)inaf.it
(End) P. Romano [INAF-IASF Palermo, Italy], P. Vannier [CDS] 10-Dec-2013